Facebook has announced it is suspending Cambridge Analytica, a London-based data firm, over concerns about violations of the social media site's policies.

On Friday, Facebook's vice president and deputy general counsel, Paul Grewal, said in a detailed statement that a University of Cambridge psychology professor, Alekandr Kogan, had passed Facebook user data he gained through an app on to third-parties, including Cambridge Analytica - a breach of the social media site's policies on protecting people's information.

Grewal said in the statement that after the discovery of this violation in 2015, Facebook "demanded certifications from Kogan and all parties he had given data to that the information had been destroyed."

Despite telling the company that the data was destroyed, the Facebook statement said it recently received reports that indicated otherwise and was suspending Cambridge Analytica, its parent company, Strategic Communication Laboratories, Kogan and another person he shared the information with, Christopher Wylie, of Eunoia Technologies Inc.

"We are committed to vigorously enforcing our policies to protect people's information," Grewal's statement said. "We will take whatever steps are required to see that this happens. We will take legal action if necessary to hold them responsible and accountable for any unlawful behavior."

In a statement, a spokesperson for Cambridge Analytica denied that the organization is in violation of Facebook's terms and said it is in communication with Facebook following the news it had been suspended from the platform.

The spokesperson said that in 2014, Cambridge Analytica contracted with Kogan's company Global Science Research (GSR) "to undertake a large scale research project in the United States," obtaining data and seeking "the informed consent of each respondent."

"When it subsequently became clear that the data had not been obtained by GSR in line with Facebook's terms of service, Cambridge Analytica deleted all data received from GSR," the spokesperson added.

"We worked with Facebook over this period to ensure that they were satisfied that we had not knowingly breached any of Facebook's terms of service and also provided a signed statement to confirm that all Facebook data and their derivatives had been deleted.

No data from GSR was used by Cambridge Analytica as part of the services it provided to the Donald Trump 2016 presidential campaign."

Facebook vice president Andrew Bosworth said the incident wasn't a data breach.

This was unequivocally not a data breach. People chose to share their data with third party apps and if those third party apps did not follow the data agreements with us/users it is a violation. no systems were infiltrated, no passwords or information were stolen or hacked.

"People chose to share their data with third party apps and if those third party apps did not follow the data agreements with us/users it is a violation. no systems were infiltrated, no passwords or information were stolen or hacked," he tweeted on Saturday.

Cambridge University officials acknowledged they knew of Kogan's company, GSR, but said they do not believe "he used University data or facilities for his work with GSR, and therefore that there is no reason to believe the University's data and facilities were used as the basis for GSR's subsequent work with any other party."

"It is important to make clear that, despite its name, Cambridge Analytica has no connection or association with the University whatsoever."

Cambridge Analytica was hired in summer 2016 as part of the Trump campaign's three-pronged data operation.

Former White House chief strategist Steve Bannon served as vice president and secretary of Cambridge Analytica until he stepped down to run the Trump campaign in August 2016.

CNN previously reported in October 2017 that the firm had contacted WikiLeaks founder Julian Assange in 2016 regarding thousands of Hillary Clinton's emails kept on a private server while she was secretary of state, according to four sources familiar with the outreach.

Cambridge Analytica CEO Aleander Nix sent an email that said he had reached out to Assange in attempt to access emails from Clinton's private server in hopes of creating a searchable database of emails for the campaign or a pro-Trump political action committee, according to two sources.

CNN reported that no one from the Trump campaign was copied on the email, the sources said. Nix sent the email in the summer of 2016, two sources said, but it is not clear whether he sent it before or after Cambridge Analytica was brought onto the campaign.